/Engine/Plugins/Runtime/ChunkDownloader/Source/Public/ChunkDownloader.h
Download and mount all chunks then fire the callback (convenience wrapper managing multiple MountChunk calls)
void MountChunks ( const [TArray](API\Runtime\Core\Containers\TArray)< int32 > & ChunkIds, const [FCallback](API\Plugins\ChunkDownloader\FChunkDownloader\FCallback) & Callback )